Land Rover/Range Rover Service Bulletin 8/86

The following is intended as an aid for the diagnosis and solution of vibration problems on 1986 model year Range Rovers. When investigating complaints of vibration in the vehicle, it is important that the vehicle is assessed in a logical manner, so that, by a process of elimination, it is possible to determine the exact source of the problem. Therefore the first part of this bulletin gives a step by step sequence for the diagnosis of vibration sources and their elimination. Before initiating any investigation, however, check the vehicle to ensure that the cause is not due to an obviously simple fault. For example: check that all engine and gearbox mountings are of the correct specification and are correctly fitted; check that all exhaust mountings are correctly fitted, in particular check that there is no metal to metal contact between the mountings and the body; check the torque of the propshaft drive flange bolts, the universal joints for excessive play and transfer box and differential bearings for excessive wear.

If your initial investigations do not identify a problem it will be necessary to carry out the following procedure, which will involve some testing of the vehicle.

NOTE: Should it be found at the outset that several vibrations are evident at different road or engine speeds, each must be treated individually. It is highly unlikely that the vibrations will be due to the same problem and therefore each will require a separate cure.

Similarly, if a vehicle is found to be suffering from a particularly harsh vibration, it may not be possible to detect other, less noticeable vibrations which may exist. However, once the primary vibration has been eliminated, the secondary vibration, which again will only be evident at different road or engine speeds, will then become prominent. Again each vibration must be treated separately, allowing the causes to be isolated and the necessary remedial action taken.

8. Fit the vibration damper assembly to the front axle, (see Attachment 1). (The attachment contains some figures. For further information, please contact Internet E-mail address: bjjen13b@telepost.no).Refit the front propshaft and road test. Is the problem still evident?

YES: Repeat diagnosis.
NO: ------.

9. Does the problem occur at 80-80 mph (112-129 kph) in ALL the available gears?

YES: Check that the rear propshaft is correctly fitted. The front and rear yokes must be IN LINE. There should be no phase difference. Realign if necessary and re-test. If problem persists, check ALL wheel and tyre assemblies for balance. If problem still evident CHECK 10.
NO: CHECK 19.

10. Mark the drive flanges and remove the rear propshaft. Secure the transmission brake drum with the propshaft flange nuts. With the differential lock engaged, re-test the vehicle. Is the problem still evident?

YES: CHECK 11.
NO: CHECK 15.

11. Remove the transmission brake drum and re-test. Is the problem still evident?